A frit material is a paste-like mixture composed of an inorganic material and an organic material and having a certain viscosity. It has advantages in low costs and simple process. Further, after being melted by laser, the frit material becomes an inorganic material, which has very good barrier performance against water and oxygen. Hence, currently, the packaging technology using the frit is the primary technology in packaging for mass-producing OLED (Organic Light-Emitting Display), and can impart the packaged OLED device long life-time.
Since the frit material is applied on the packaging region of the substrate to be packaged, it needs to undergo patterning processes, such as screening, dispensing, and the like, to form corresponding patterns. Therefore, main part of the organic material in the frit material is the organic thickener, which has the function of dispersing inorganic materials, such as frit-powders in the form of powder. If the amount of the organic thickener component is too small, it is difficult to enable the frit material to form a paste-like mixture having a certain viscosity, and thus difficult to be applied to form patterns.
Further, when the organic material is irradiated by laser, a flash explosion may occur, and harmful gas that affects the OLED device may be generated. Therefore, before the frit material is subjected to laser melting, it needs to undergo a pretreatment by sintering it at high temperature, so as to remove the organic materials by evaporation. Then, the frit material is adhered to the device substrate having OLED device formed thereon, to perform the laser packaging process.
However, the organic material will produce bubbles during the sintering at high temperature, while the thickness of the frit material applied on the substrate to be packaged is relatively small (generally, less than 10 μm). Therefore, the bubbles affect the morphology of the surface and interior of the frit material relatively greatly. The movement of the bubbles to the surface of the frit material under the influence of the high temperature will make the surface uneven. Hence, after the frit material is adhered to the device substrate, some regions of the device substrate actually are not in contact with the frit material. It results in poor package after the irradiation by laser, which reduces the mechanical strength of the packaged OLED panel. Additionally, inside the frit material, after the organic material is evaporated, it leaves bubbles, which can increase the inner stress of the frit material after being melted and cured, and further reduce the mechanical strength of the packaged OLED panel.